This invention relates to a method of and apparatus for testing airtightness of a closed space, which closed space is provided with a steam movement control device which is used as a humidifier, a dehumidifier and a humidity regulator, by controlling a direction of steam movement with specific waterproof membranes and their arrangement.
The inventor has already disclosed a steam movement control device in Japanese Patent Laid-Open Publication No. 322060/1993. The steam movement control device has one ventilation hole communicated to an interior of a housing (closed space) and the other opened to atmospheric air. Multiple small chambers, which are separated by air and water vapor permeable, waterproof membranes, exist between the two ventilation holes. Steam movement is controlled so as to eliminate, add, or control humidity in the housing by applying air and water vapor permeability of waterproof membranes with temperature fluctuation speed between outdoor air and the housing.
The steam movement control device is, as shown above, attached to the housing (closed space). The steam movement control device functions on the condition that the airtightness of the housing (closed space) is maintained. Leakage which underruns the moisture control ability of the steam movement control device is tolerated because the leakage can be compensated by the moisture control ability of the device itself.
However, methods to confirm the airtightness of the housing (closed space) have not been established yet. At present, the airtightness is, at best, maintained by adopting a temporary drip proof or airtight structure. There are no methods to check the airtight state of a housing with a steam movement control device attached.
This invention was devised in consideration of the actual state of art. The purpose of this invention is to offer a method of and an apparatus for testing airtightness of a closed space, which airtightness is a prerequisite for installation of a steam movement control device.
The method of testing airtightness according to this invention is intended for a closed space which has two ventilation holes; one of which is communicated to an interior of a housing, and the other is opened to atompspheric air, and between said two ventilation holes small chambers are separated by air and humidity permeable, waterproof membranes and which is provided with a steam movement control device to control steam movement between said two ventilation holes. The configuration is that while predetermined pressure gas is injected into the closed space from an air feed passage to said closed space, pressure is measured in an air exhaust passage from the closed space and a measured pressure value is compared with an injection pressure value, and it is recognized that when the measured pressure value is substantially equal to the injection pressure value, airtightness in the housing is maintained, and when the measured pressure value is lower than the injection value, airtightness leaks.
The airtightness testing device which corresponds to this airtightness testing method is equipped with an air feed passage and an air exhaust passage communicated to the interior of the closed space. The air feed passage is connected with a gas injection device which feeds the gas at a predetermined pressure and the air exhaust passage is connected with a pressure gauge.
The airtightness testing method according to this invention is that while predetermined pressure gas is injected into a test space which communicates to inside of the closed space through a ventilation passage, pressure is measured in the test space and the measured pressure value is compared with a pressure value before injection, and it is recognized that when the measured pressure value is higher than the pressure value before injection, airtightness in the housing is maintained, and when the measured pressure value is substantially equal to the pressure value before injection, airtightness leaks.
The airtightness testing device which corresponds to this airtightness testing method is composed of a test space which communicates to the inside of the closed space through a ventilation passage, a gas injection device which supplies gas at a predetermined pressure and a pressure gauge to measure the pressure in the test space.
The said airtightness testing device is equipped with a closed space connection part which consists of a double tube, which tube is made up with an inner tube forming an air feed passage and an outer tube forming air exhaust passage. This closed space connection part is connected in detachable way to a connection hole which is formed on the closed space, and the inner tube protrudes from the end of the outer tube. Thus, the openings of the inner tube and the outer tube are distant from each other. In this case, the inner tube is formed with retractility to make the inner tube protruded from the outer tube opening at the extended state.
In the airtightness testing method, even when the airtightness of the closed space is recognized to leak, if the degree of leakage underruns the moisture control ability of the steam movement control device, the leakage does not necessarily be assumed to be a failure as the steam movement control device can function.